/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.bangcommunity.bbframe.common.utils.reflect;

/**
 * Handy class for wrapping runtime {@code Exceptions} with a root cause.
 *
 * <p>
 * This class is {@code abstract} to force the programmer to extend the class. {@code getMessage}
 * will include nested exception information; {@code printStackTrace} and other like methods will
 * delegate to the wrapped exception, if any.
 *
 * <p>
 * The similarity between this class and the {@link NestedCheckedException} class is unavoidable, as
 * Java forces these two classes to have different superclasses (ah, the inflexibility of concrete
 * inheritance!).
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @see #getMessage
 * @see #printStackTrace
 */
public abstract class NestedRuntimeException extends RuntimeException {

    /** Use serialVersionUID from Spring 1.2 for interoperability */
    private static final long serialVersionUID = 5439915454935047936L;

    /**
     * Construct a {@code NestedRuntimeException} with the specified detail message.
     * 
     * @param msg
     *            the detail message
     */
    public NestedRuntimeException(String msg) {
        super(msg);
    }

    /**
     * Construct a {@code NestedRuntimeException} with the specified detail message and nested
     * exception.
     * 
     * @param msg
     *            the detail message
     * @param cause
     *            the nested exception
     */
    public NestedRuntimeException(String msg, Throwable cause) {
        super(msg, cause);
    }

    /**
     * Retrieve the innermost cause of this exception, if any.
     * 
     * @return the innermost exception, or {@code null} if none
     * @since 2.0
     */
    public Throwable getRootCause() {
        Throwable rootCause = null;
        Throwable cause = getCause();
        while (cause != null && cause != rootCause) {
            rootCause = cause;
            cause = cause.getCause();
        }
        return rootCause;
    }

    /**
     * Retrieve the most specific cause of this exception, that is, either the innermost cause (root
     * cause) or this exception itself.
     * <p>
     * Differs from {@link #getRootCause()} in that it falls back to the present exception if there
     * is no root cause.
     * 
     * @return the most specific cause (never {@code null})
     * @since 2.0.3
     */
    public Throwable getMostSpecificCause() {
        Throwable rootCause = getRootCause();
        return (rootCause != null ? rootCause : this);
    }

    /**
     * Check whether this exception contains an exception of the given type: either it is of the
     * given class itself or it contains a nested cause of the given type.
     * 
     * @param exType
     *            the exception type to look for
     * @return whether there is a nested exception of the specified type
     */
    public boolean contains(Class<?> exType) {
        if (exType == null) {
            return false;
        }
        if (exType.isInstance(this)) {
            return true;
        }
        Throwable cause = getCause();
        if (cause == this) {
            return false;
        }
        if (cause instanceof NestedRuntimeException) {
            return ((NestedRuntimeException) cause).contains(exType);
        } else {
            while (cause != null) {
                if (exType.isInstance(cause)) {
                    return true;
                }
                if (cause.getCause() == cause) {
                    break;
                }
                cause = cause.getCause();
            }
            return false;
        }
    }

}
